Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description reinforces this with a billing-specific guarantee that nothing is created or charged, which is meaningfully more than readOnlyHint conveys. It stops short of stating units, currency, or whether estimates can drift from the final charge.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences with zero waste; the value proposition comes first and the no-side-effect reassurance second. Nothing could be removed without losing information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description does supply the key return semantic (an exact charge amount) and removes the safety question an agent would otherwise have. It could go further by specifying the response shape or currency, which is the only real gap for a two-parameter read-only tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both parameters (model, input) are already documented in the schema, including the note that input mirrors get_model's camelCase parameters. The description adds the framing that the request shape matches create_generation, but no new syntax or format detail, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states precisely what the tool returns ("the exact amount create_generation would charge for this request") and implicitly ties it to the sibling that performs the actual creation. An agent can distinguish it from create_generation without opening either schema, though the phrasing is a noun clause rather than an explicit verb+resource statement.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The reference to create_generation and the assurance that nothing is created or charged imply the intended use as a pre-flight dry run, but the description never says explicitly when to call it (e.g., "call before create_generation") or when alternatives are preferable.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.